According to eMarketer, Twitter grossed $129.7 million in mobile ad sales in the U.S. vs. Facebook’s $72.7 million. To some extent, that’s not saying much, since Google and even Pandora, each selling mobile ads for at least a couple of years now, beat both of those companies. In particular, Google dominates thanks to its mobile search ads, which constitute more than half of all mobile ads, though for display ads alone, Google is just barely ahead of Pandora.

Overall, according to eMarketer’s crystal ball, mobile ad sales will total $2.61 billion this year, rising to $12 billion by 2016 (though you’d do well not to put too much stock in forecasts that far out). These are net revenues after paying distribution partners. This year’s tally is still only about 1% of overall online ad sales.

eMarketer’s capsule analysis of Facebook’s and Twitter’s mobile results and prospects indicates the latter company won’t keep its lead for long. …